Here is a softer 13-color palette based on the original colors while maintaining a similar aesthetic:

json
{
  "palette_name": "Soft Contrast Spectrum",
  "colors": [
    {
      "name": "Soft Red",
      "hex_code": "
                            
                            #F08080
                        "
    },
    {
      "name": "Sky Blue",
      "hex_code": "
                            
                            #87CEEB
                        "
    },
    {
      "name": "Pastel Green",
      "hex_code": "
                            
                            #98FB98
                        "
    },
    {
      "name": "Light Yellow",
      "hex_code": "
                            
                            #FFFACD
                        "
    },
    {
      "name": "Lavender",
      "hex_code": "
                            
                            #E6E6FA
                        "
    },
    {
      "name": "Peach",
      "hex_code": "
                            
                            #FFDAB9
                        "
    },
    {
      "name": "Light Slate Gray",
      "hex_code": "
                            
                            #B0C4DE
                        "
    },
    {
      "name": "Medium Turquoise",
      "hex_code": "
                            
                            #48D1CC
                        "
    },
    {
      "name": "Light Cyan",
      "hex_code": "
                            
                            #E0FFFF
                        "
    },
    {
      "name": "Mellow Lime",
      "hex_code": "
                            
                            #D3FFCE
                        "
    },
    {
      "name": "Powder Blue",
      "hex_code": "
                            
                            #B0E0E6
                        "
    },
    {
      "name": "Sandy Brown",
      "hex_code": "
                            
                            #F4A460
                        "
    },
    {
      "name": "Salmon",
      "hex_code": "
                            
                            #FA8072
                        "
    }
  ]
}

This softer palette maintains a similar range of colors while opting for lighter and more muted shades to create a gentle aesthetic. If you have any additional preferences or adjustments, feel free to let me know!